Three hundred eighty-four premature infants were examined by indirect ophthalmoscopy in a period of 38 months. Sixty-eight were found to have some degree of retrolental fibroplasia. Most pathologic changes resolved spontaneously to normal or near normal. A classification was formulated, based on peripheral vascular changes, to enable observers to interpret and quantitate the amount of disease present. The role of the ophtalmologist in the perinatal intensive care nursery is not to dictate the amount of oxygen administration during the acute phase of respiratory distress syndrome but to monitor peripheral fundus and posterior vascular changes of infants of low birth weight, or who have received oxygen, or both, at a time that is not detrimental to the health of the infant. To evaluate the possible indications and efficacy of surgical intervention, an understanding of the natural course of the disease process is mandatory.